Washing plant



C. H. SPlLLER April 3, 1956 WASHING PLANT Filed June 20, 1952 FIGURE l United States Patent G wasmo PLANT Clifford Harry Spiller, Woodlands, Doneaster, England, assignor to Coal Industry (Patents) Limited, London, England, a corporation of Great Britain Application June 20, 1952, Serial No. 294,681

Claims priority, application Great Britain July 2, 1951 3 Claims. (Cl. 2il 455) This invention relates to wash boxes for cleaning minerals or carbonaceous materials, for example coal.

One object of the invention is to provide an improved wash box comprising a sieve or grid which supports the cleaned material and the larger pieces of foreign matter and allows the finer particles of foreign matter to fall to the bottom of the wash box.

In such wash boxes the finer dirt particles are usually removed from the bottom of the wash box by means of a worm conveyor. However, it has been found in practice that the maintenance of the worm conveyor is troublesome and expensive.

According to the invention a wash box for cleaning minerals or carbonaceous materials, for example coal, comprising a sieve or grid which supports the cleaned material and the larger pieces of foreign matter and allows the finer particles of foreign matter to fall to the bottom of the wash box, is characterised in that the finer particles of foreign matter are moved along the bottom of the wash box by one or more jets or currents of liquid. The wash box may advantageously be of the Baum type in which the level of the liquid (conveniently water) in the wash box is caused to perform an up-and-down oscillatory movement. Preferably the jets or currents are caused by discharging liquid from nozzles in a direction substantially parallel to the bottom of the wash box. In a particularly advantageous construction the oscillatory movement of the liquid level is caused by compressing and evacuating or releasing air in a compartment bounded at the bottom by part of the liquid surface, and the discharge of liquid from the nozzles is elfected by compressed air from the same source as the compressed air used for producing the oscillatory movement. The nozzles may conveniently be connected by pipes to the interior of the said compartment so that the variations in pressure within the compartment cause surges of pressure within the pipes and the intermittent discharge of jets of liquid from the nozzles. In a simple and suitable construction each nozzle is connected to an upwardly-directed pipe which is open-ended and terminates approximately at the mean level of the liquid in the said compartment.

In the accompanying drawing a wash box according to the invention is illustrated diagrammatically by way of example,

Figure 1 being a side elevation in section on the line 1-1 of Figure 2, and

Figure 2 being an end elevation in section on the line 11-11 of Figure 1.

Referring to the said drawing, the wash box 1 is provided with a channel-like bottom portion 1a and a compartice ment 2 which is bounded on one side by a vertical longitudinal bafiie 14 and on the bottom by part of the surface of the liquid (conveniently water) in the wash box. Water enters the wash box through an entry 3, the wash box being filled until the liquid takes up a mean level at the position indicated by the line 4. Coal and foreign matter are separated on a sieve 7 above transverse vertical baflles 13 and travel along towards a dirt elevator 12. Compressed air is admitted through a valve 10 to produce a pulsating increase and recrease in pressure in the compartment 2 so that the level of the liquid in the wash box is caused to perform an up and down oscillatory move ment and the finer particles of foreign matter or dirt fall through the sieve into the bottom portion 1a of the wash box. Arranged in the channel-like bottom portion 1a are several nozzles 8 which are directed horizontally and approximately parallel to the bottom of the box. Each nozzle 8 is connected to a pipe 9 which is upwardly directed and open at the top end where it terminates approximately at the mean level 4 of the liquid in the compartment 2. The pulsating pressure in the compartment 2 thus causes intermittent or pulsating jets or currents to be discharged from the nozzles 8, and these jets or currents move the finer particles of foreign matter along the bottom of the wash box to the dirt elevator 12 by means of which the dirt is removed.

The cleaned coal 5 is separated in known manner by a conventional separating device 11 from the coarse particles and lumps of rejected material 6 such as dirt, rock and slate which falls into and is removed by the dirt elevator 12.

I claim:

1. A wash box for cleaning minerals or carbonaceous materials comprising a source of pulsating air pressure, means associated with said source to create pulsating movement of the liquid level in said wash box, a grid adaped to support cleaned material and larger pieces of foreign matter while allowing the finer particles of foreign matter to fall to the bottom of said wash box, means defining an outlet for said finer particles from said washbox, a plurality of nozzles directed along the bottom of the wash box towards said outlet, and further means associated with said source for applying a pulsating pressure to said nozzles to cause associated pulsating jets of liquid to issue from said nozzles.

2. A wash box according to claim 1 comprising a compartment for air bounded at the bottom by part of the liquid surface in the wash box, and piping connecting said nozzles to said compartment whereby variations in pressure within said compartment cause corresponding surges of pressure within said piping and corresponding intermittent discharge of jets of liquid from said nozzles.

3. A wash box according to claim 1 wherein the said piping comprises an upwardly directed portion to which each nozzle is connected, the said portion being open at its upper end and terminating approximately at the mean level of the liquid in the said compartment.

OTHER REFERENCES Coal Preparation, 2nd edition, published by the A. I. M. M. E., New York, 1950, pages 407 to 422. 

